NEW YORK (AP) — CNN's medical correspondent Dr. Sanjay Gupta has taken the unusual step of publicly urging Attorney General Jeff Sessions to reconsider his opposition to medical marijuana, particularly as a way to fight the opioid epidemic.

Gupta wrote a public letter to Sessions, saying that he had changed his mind on the use of medical marijuana, "and I am certain you can, as well."

He said he made his plea after Sessions declined to be interviewed for his special on the topic, which airs Sunday night at 8 p.m. EDT on CNN. A spokeswoman for Sessions declined comment on Thursday.

The CNN special follows football player Mike James and others who say that medical marijuana has both eased the pain of injuries and weaned them from addiction to opioids. Medical marijuana is currently legal in 29 states and Washington, D.C.

Before he began researching the issue a few years ago, Gupta said he was not a believer in medical marijuana and, in fact, thought it was essentially being used as a ladder to recreational use of the drug. But he said he became convinced that research on the issue was intentionally skewed negative, and he spoke to enough people who swear by it.

"The idea that it could work for people, and sometimes is the only thing than can work for people, should give it the respect that it deserves," he said in an interview.

Still, reporters generally tell stories and don't become advocates the way Gupta has by writing to Sessions.

"I don't see it, first of all, as a step into advocacy," he said. "As a journalist, one of the things that we're obligated to do is speak truth to power and this is a good example of that."

The opioid epidemic lends urgency to the issue, he said.

The special quotes Sessions in a public appearance saying "how stupid is that" to the opinion that medical marijuana could be used to stem heroin addiction.

Gupta said the marijuana use needs to be carefully regulated and tested to determine the correct dosages. In his letter to Sessions, Gupta said that if researchers started from scratch to design a medicine to help turn around the opioid epidemic, it would likely look like cannabis.

He said he's not morally opposed to recreational use of marijuana, which is legal in nine states and the District of Columbia. But he said he didn't want to confuse the two issues.

"People comingle the two issues and I think it's really hurt the medical marijuana movement," he said.

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